To play devil's advocate (because I like turret gunners

)...
That's fine, and quite well arranged in fact. But is there any reason to actually fire the gun from the turret under normal circumstances?
One leaps to mind, no chance of other damage (like say bridge, computer, crew, or power* hits) resulting in the turret being unable to fire. Local control means only if the turret is hit will it not be able to fire. Granted Traveller doesn't model this, so it's very much a MTU refinement.
* for missiles only of course, losing power means no energy weapons naturally
There's also the volume issue. I find 1ton works for the whole deal, turret, weapons space, fire control, and gunner station. I didn't find the idea of it being all control (fire control and gunner station) per the early rules satisfactory. Neither did I see making it all weapon as suitable either.
So imtu you designate a hardpoint(s) and reserve tonnage locally for the system. Until installed that tonnage could be put to other limited uses, but you could not decide to mount a weapon somewhere else.
Couldn't it be operated from a bridge workstation...
It could, and can be imtu, any other workstation in fact (all can double for any other, one could even fly the ship from a connected turret workstation), but with less functionality since it's not a dedicated station. Only the local station grants full functionality.
...assuming the assistance of a sophant is needed?
Naturally. That's a core condition of CT.
And wouldn't that usually be preferable? The gunner has better protection, and is in closer communication with the captain, the sensor officers, etc as well as being able to see the information from the bridge computers at a glance.
I don't see why. Better protection? Not suggested by the rules in any way. Closer communication with others? Trades off closer communication with the weapon. Being able to see the bridge displays would help targeting how? More likely to me that the dedicated displays of the turret would be preferred. And if you're giving the gunners their own tactical share of the bridge displays you're doing it by reducing that of the rest of the crew there.
One thing I have done, given the increasing size of the bridge in very large ships is set some of it aside for gunners operating batteries and heavy weapons. There is still a workstation and control local to turrets but generally unmanned. If your fire control is disabled (damage reducing batteries) you may still (if sufficiently crewed) man the turrets and return some of them to combat. But again that's a mtu refinement, not official.
And finally, imtu, turrets also serve as escape pods for the gunner manning the turret. A turret kill imtu is usually due to damage that fires the auto eject. Damage which would have resulted in the turret being destroyed and doing more damage to the ship if it hadn't been ejected. The workstation separates from the rest and the gunner (who should be wearing imtu combat armour vacc suit) drifts and waits (extra LS in the ejection seat) to be picked up by search and rescue or captured by the enemy. Most other crew have to rely on boats or simply abandon ship by vacc-suit out an airlock, and they have little chance in a catastrophic hit.